The AQP-3 water channel is a pivotal modulator of glycerol-induced chloride channel activation in nasopharyngeal carcinoma cells

The rhizomes of Atractylodes macrocephala Koidz improve gastrointestinal health and pregnancy outcomes in pregnant mice via modulating intestinal barrier and water-fluid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Baizhu (BZ) is the dried rhizome of Atractylodes macrocephala Koidz (Compositae), which invigorates the spleen, improves vital energy, stabilizes the fetus, and is widely used for treating spleen deficiency syndrome. However, the impact of BZ on gastrointestinal function during pregnancy remains unexplored.

AIM OF THE STUDY

This study elucidated the ameliorative effects of BZ on gastrointestinal health and pregnancy outcomes in pregnant mice with spleen deficiency diarrhea (SDD).

METHODS

To simulate an irregular human diet and overconsumption of cold and bitter foods leading to SDD, a model of pregnant mice with SDD was established using an alternate-day fasting and high-fat diet combined with oral administration of Sennae Folium. During the experiment, general indicators and diarrhea-related parameters were measured. Gastric and intestinal motility (small intestinal propulsion and gastric emptying rates) were evaluated. Serum motilin (MTL), ghrelin, growth hormone (GH), gastrin (Gas), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), chorionic gonadotropin β (β-CG), progesterone (P), and estradiol (E2) were quantified using an enzyme-linked immunosorbent assay. Pathological changes were examined by hematoxylin and eosin staining (H&E) and alcian blue periodic acid Schiff staining (AB-PAS). Immunohistochemistry and immunofluorescence were used to measure the expression levels of the intestinal barrier and water metabolism-related proteins in colonic tissues. The pregnancy rate, ovarian organ coefficient, uterus with fetus organ coefficient, small size, average fetal weight, and body length of fetal mice were calculated.

RESULTS

The results showed that BZ significantly improved general indicators and diarrhea in pregnant mice with SDD, increased gastric emptying rate and small intestinal propulsion rate, elevated the levels of gastrointestinal hormones (AMS, ghrelin, GH, and Gas) in the serum, and reduced lipid levels (TC and LDL-c). It also improved colonic tissue morphology, increased the number of goblet cells, and promoted the mRNA and protein expression of occludin, claudin-1, ZO-1, AQP3, AQP4, and AQP8 in colonic tissues, downregulating the mRNA and protein expression levels of claudin-2, thereby alleviating intestinal barrier damage and regulating the balance of water and fluid metabolism. BZ also held the levels of pregnancy hormones (β-CG, P, and E2) in the serum of pregnant mice with SDD. Moreover, it increased the pregnancy rate, ovarian organ coefficient, uterus with fetus organ coefficient, litter size, average fetal weight, and body length of fetal mice. These findings indicate that BZ can improve spleen deficiency-related symptoms in pregnant mice before and during pregnancy, regulate pregnancy-related hormones, and improve pregnancy outcomes.

Influence of copper source and dietary inclusion level on growth performance of weaned pigs and expression of trace element related genes in the small intestine

Copper is routinely supplemented to weanling pig diets at concentrations above nutritional requirements to enhance growth performance. We hypothesised that this effect depends on the source of Cu and its dietary concentration. We tested this in weaned pigs (26 d of age) over a 35-d period using a 2 × 3 factorial arrangement with two Cu-sources (CuSO4 and Cu2O, monovalent copper oxide, CoRouge®) and three supplementary dietary Cu-levels (15, 80 and 160 mg Cu/kg) as respective factors. Increasing Cu level linearly increased (P < 0.001) final BW and daily gain. These effects tended (P = 0.09) to be greater with Cu2O than CuSO4. Feed conversion ratio decreased linearly (P < 0.001) with increasing dietary Cu content, independent of Cu source. Plasma Cu, Zn and Fe levels were unaffected, whereas liver Cu content increased quadratically (P < 0.001) with increasing dietary Cu content, with a larger increase (P < 0.001) with CuSO4 than Cu2O. Bile Cu content increased quadratically (P = 0.025) with increasing Cu content, irrespective of Cu source. RT-qPCR analysis revealed that increasing Cu content quadratically (P = 0.009) increased duodenal but not ileal metallothionein 1A (MT1A) mRNA, with greater effect (P = 0.010) of CuSO4. Regardless of the Cu source, increasing Cu dose linearly increased (P = 0.006) duodenal DMT1/SLC11A2 mRNA but decreased ZIP4/SLC39A4 mRNA in duodenum (P < 0.001) and ileum (P < 0.005). ZnT10/SLC30A10 mRNA was significantly (P = 0.021) and numerically (P = 0.061) greater with Cu2O compared to CuSO4, in duodenum and ileum, respectively. Copper content quadratically modulated duodenal but not ileal transferrin receptor (P = 0.029) and ferric reductase CYBRD1 mRNA (P = 0.022). In hypothalamus, high Cu dose (P = 0.024) and Cu2O as source (P = 0.028) reduced corticotropin-releasing hormone (CRH) mRNA. Low versus high CuSO4 increased corticotropin-releasing hormone receptor (CRHR2) mRNA, while low Cu2O had the opposite effect (P = 0.009). In conclusion, incremental Cu intake enhanced growth performance, with a tendency for a greater effect of Cu2O. The lower increase in duodenal MT1A mRNA and liver Cu content indicates that less Cu from Cu2O was absorbed by gut and sequestered in liver. Thus, high Cu absorption is not essential for its growth-promoting effect and dietary Cu may affect intestinal Fe and Zn absorption via the active, transcellular route. The effects on hypothalamic CRH and CRHR2 expression indicate a role for the hypothalamus in mediating the effects of Cu on growth performance.

Insight into the Mammalian Aquaporin Interactome

Aquaporins (AQPs) are a family of transmembrane water channels expressed in all living organisms. AQPs facilitate osmotically driven water flux across biological membranes and, in some cases, the movement of small molecules (such as glycerol, urea, CO₂, NH₃, H₂O₂). Protein-protein interactions play essential roles in protein regulation and function. This review provides a comprehensive overview of the current knowledge of the AQP interactomes and addresses the molecular basis and functional significance of these protein-protein interactions in health and diseases. Targeting AQP interactomes may offer new therapeutic avenues as targeting individual AQPs remains challenging despite intense efforts.

The Mechanism of Bone Remodeling After Bone Aging

Senescence mainly manifests as a series of degenerative changes in the morphological structure and function of the body. Osteoporosis is a systemic bone metabolic disease characterized by destruction of bone microstructure, low bone mineral content, decreased bone strength, and increased brittleness and fracture susceptibility. Osteoblasts, osteoclasts and osteocytes are the main cellular components of bones. However, in the process of aging, due to various self or environmental factors, the body’s function and metabolism are disordered, and osteoporosis will appear in the bones. Here, we summarize the mechanism of aging, and focus on the impact of aging on bone remodeling homeostasis, including the mechanism of ion channels on bone remodeling. Finally, we summarized the current clinical medications, targets and defects for the treatment of osteoporosis.

Chloride Channel and Inflammation-Mediated Pathogenesis of Osteoarthritis

Articular cartilage allows the human body to buffer and absorb stress during normal exercise. It is mainly composed of cartilage cells and the extracellular matrix and is surrounded by the extracellular microenvironment formed by synovial fluid and various factors in it. Studies have shown that chondrocytes are the metabolic center of articular cartilage. Under physiological conditions, the extracellular matrix is in a dynamic balance of anabolism and catabolism, and various factors and physical and chemical conditions in the extracellular microenvironment are also in a steady state. This homeostasis depends on the normal function of proteins represented by various ion channels on chondrocytes. In mammalian chondrocyte species, ion channels are mainly divided into two categories: cation channels and anion channels. Anion channels such as chloride channels have become hot research topics in recent years. These channels play an extremely important role in various physiological processes. Recently, a growing body of evidence has shown that many pathological processes, abnormal concentration of mechanical stress and chloride channel dysfunction in articular cartilage lead to microenvironment disorders, matrix and bone metabolism imbalances, which cause partial aseptic inflammation. These pathological processes initiate extracellular matrix degradation, abnormal chondrocyte death, hyperplasia of inflammatory synovium and bony. Osteoarthritis (OA) is a common clinical disease in orthopedics. Its typical manifestations are joint inflammation and pain caused by articular cartilage degeneration, but its pathogenesis has not been fully elucidated. Focusing on the physiological functions and pathological changes of chloride channels and pathophysiology of aseptic inflammation furthers the understanding of OA pathogenesis and provides possible targets for subsequent medication development.

Interleukin 1 beta-induced chloride currents are important in osteoarthritis onset: an in vitro study

Persistent hypotonic and inflammatory conditions in the joint cavity can lead to the loss of cartilage matrix and cell death, which are the important mechanisms of osteoarthritis (OA) onset. Previous studies have confirmed that the existence of a hypotonic environment is a red flag for inflammation, as hypotonic environment induces the opening of the chloride channel of the cell and promotes chloride ion efflux, which prompts the cell volume to increase. Chloride channels play an important role in the regulation of mineralization and chondrocyte death. Here, we reported that OA chondrocytes showed a significant increase of cell death rate and the imbalance of cartilage matrix catabolism. We found that the distribution of skeleton protein F-actin was disordered. In addition, the volume-sensitive chloride current of OA chondrocytes decreased significantly with the increase of the expression levels of inflammation-related proteins caspase-1, caspase-3, and NLRP3. Moreover, interleukin-1β (IL-1β) showed a potential to activate the chloride current of normal chondrocytes. These results indicate that IL-1β-induced chloride channel opening in chondrocytes may be closely related to the occurrence of OA. This chloride channel opening process may therefore be a potential target for the treatment of OA.

Identification of the AQP8-miR-92a network associated with the aggressive traits of colorectal cancer

Even though earlier reports have revealed that Aquaporin 8 (AQP8) exert essential roles in diverse malignancies, its relationship between specific microRNAs (miRNAs) in regulation of colorectal carcinoma (CRC) progression has never been elaborated. Herein, we proved that AQP8 was downregulated in CRC and high level of AQP8 was significantly associated with better survival in CRC patients. Overexpression of AQP8 restrained CRC cell proliferation, migration and invasion capacities in vitro. In vivo, upregulation of AQP8 also suppressed CRC cell growth. Mechanistic analyses illustrated that AQP8 was a directly target of miR-92a. The expression of AQP8 was negatively modulated by miR-92a. Rescues analysis indicated that miR-92a facilitated CRC cell growth and invasion via modulating the expression of AQP8. Our work validated that miR-92a regulated the aggressiveness of CRC cell via targeting AQP8.

Deep-Fried Atractylodis Rhizoma Protects against Spleen Deficiency-Induced Diarrhea through Regulating Intestinal Inflammatory Response and Gut Microbiota

According to the theories of traditional Chinese medicine, spleen deficiency often leads to diarrhea, and deep-fried Atractylodis Rhizoma (DAR) is commonly used for the treatment. However, the association between spleen deficiency and diarrhea remains unclear. The present study aimed to investigate the therapeutic effect of DAR for the treatment of diarrhea caused by spleen deficiency and analyze the related mechanisms. It was found that a high dose group of an ethanolic extract of deep-fried Atractylodis Rhizoma (EEDAR-H) significantly inhibited weight loss, diarrhea, and pathological changes in colon tissue induced by rhubarb. EEDAR-H was found to significantly reduce the level of intestinal inflammatory cytokines and increase the expression of gastrointestinal motility hormones. In addition, EEDAR-H significantly increased the expression of aquaporin 3 (AQP3) and aquaporin 8 (AQP8) and restored abnormal water metabolism; Shen-Ling-Bai-Zhu-San (SLBZS) induced the same effect as EEDAR-H. Additional tests on the mechanism found that EEDAR-H and SLBZS promoted the integrity of the intestinal barrier. Both significantly increased the expression of the tight junction protein ZO-1 and Occludin, inhibited the phosphorylation of p38MAPK and MLC, and significantly reduced the expression levels of PAR-2. Analysis of the gut microbiota indicated that overall changes in its structure were reversed after treatment with EEDAR-H or SLBZS, in addition to significant modulation of the abundance of different phyla. At the genus level, EEDAR-H or SLBZS significantly reduced the levels of potential pathogens and increased those of beneficial bacteria.

Prognostic implications of Aquaporin 9 expression in clear cell renal cell carcinoma

Background

Growing evidence has demonstrated immune reactivity as a confirmed important carcinogenesis and therapy efficacy for clear cell renal cell carcinoma (ccRCC). Aquaporin 9 (AQP9) is involved in many immune-related signals; however, its role in ccRCC remains to be elucidated. This study investigated AQP9 expression in tumor tissues and defined the prognostic value in ccRCC patients.

Methods

A total of 913 ccRCC patients with available RNA-sequence data from the Cancer Genome Atlas (TCGA) database and Fudan University Shanghai Cancer Center (FUSCC) were consecutively recruited in analyses. Differential transcriptional and proteome expression profiles were obtained and validated using multiple datasets. A partial likelihood test from Cox regression analysis was developed to address the influence of independent factors on progression-free survival (PFS) and overall survival (OS). The Kaplan–Meier method and log-rank test were performed to assess survival. Receiver operating characteristic (ROC) curves were used to describe binary classifier value of AQP9 using area under the curve (AUC) score. Functional enrichment analyses and immune infiltration analysis were used to describe significantly involved hallmark pathways of hub genes.

Results

Significantly elevated transcriptional and proteomic AQP9 expressions were found in ccRCC samples. Increased AQP9 mRNA expression was significantly associated with advanced clinicopathological parameters and correlated with shorter PFS and OS in TCGA and FUSCC cohorts (p < 0.001). ROC curves suggested the significant diagnostic and prognostic ability of AQP9 (PFS, AUC = 0.823; OS, AUC = 0.828). Functional annotations indicated that AQP9 is involved in the most significant hallmarks including complement, coagulation, IL6/JAK–STAT3, inflammatory response and TNF-alpha signaling pathways.

Conclusion

Our study revealed that elevated AQP9 expression was significantly correlated with aggressive progression, poor survival and immune infiltrations in ccRCC patients, and we validated its prognostic value in a real-world cohort. These data suggest that AQP9 may act as an oncogene and a promising prognostic marker in ccRCC.

Overexpression of ClC-3 Chloride Channel in Chondrosarcoma: An In Vivo Immunohistochemical Study with Tissue Microarray

Background

Recently, ClC-3 chloride channel expression has been noted to be high in some tumors. In chondrosarcoma, which is a malignant tumor with a high incidence in the bone, there has been no previous literature regarding ClC-3 chloride channel expression. Here we evaluated the expression of ClC-3 chloride channel in chondrosarcoma and explored its clinical significance.

Material/Methods

In this study, 75 chondrosarcoma and 5 normal cartilage tissues were collected. Thereafter, tissue microarray was performed. Immunohistochemistry was also used to observe the level of ClC-3 chloride channel expression between normal and chondrosarcoma tissues.

Results

Results showed that the expression of ClC-3 chloride channel in the normal chondrocyte was thinner, since it showed distinct differentiation among chondrosarcoma specimens. Interestingly, we noticed that the moderately-differentiated chondrosarcoma (MDC) and the poorly-differentiated chondrosarcoma (PDC) exhibited 94.44% of ClC-3 chloride channel. Besides, the subcellular localization of ClC-3 chloride channel was changed in association with malignant degree changes. The subcellular localization of ClC-3 chloride channel in the MDC and PDC tissue was localized in the cytoplasm and both nucleus and cytoplasm: 83.33% (5 out of 6 cases) and 91.66% (11 out of 12 cases) respectively. On the other hand, we noticed that patient age and gender could have a relation with ClC-3 chloride channel expression; 30- to 60-year-old males showed more expression.

Conclusions

These results demonstrated a high frequency of ClC-3 chloride channel overexpression and subcellular localization differences in MDC and PDC tissue, suggesting a specific role of ClC-3 chloride channel in the pathogenesis of chondrosarcoma.

ClC-3 chloride channels are involved in estradiol regulation of bone formation by MC3T3-E1 osteoblasts

Evidence has been reported by us and others supporting the important roles of chloride channels in a number of osteoblast cell functions. The ClC-3 chloride channel is activated by estradiol binding to estrogen receptor alpha on the cell membranes of osteoblasts. However, the functions of these chloride channels in estrogen regulation of osteoblast metabolism remain unclear. In the present study, the roles of chloride channels in estrogen regulation of osteoblasts were investigated in the osteoblastic cell line MC3T3-E1. Estrogen 17β-estradiol enhanced collagen I protein expression, alkaline phosphatase activity, and mineralization were inhibited, by chloride channel blockers. Estradiol promoted ClC-3 chloride channel protein expression. Silencing of ClC-3 chloride channel expression prevented the elevation of osteodifferentiation in osteoblasts, which were regulated by estrogen. These data suggest that estrogen can regulate bone formation by activating ClC-3 chloride channels and the activation of ClC-3 chloride channels can enhance the osteodifferentiation in osteoblasts.

High expression of leucine‑rich repeat‑containing 8A is indicative of a worse outcome of colon cancer patients by enhancing cancer cell growth and metastasis

To survive, cells need to avoid excessive volume change that jeopardizes structural integrity and stability of the intracellular milieu. Searching for the molecular identity of volume‑regulated anion channel (VRAC) has yielded multiple potential candidates, but none has been confirmed. Recently, it is reported that leucine‑rich repeat‑containing 8A (LRRC8A) is a main molecular determinant of VRAC current. The biological functions of LRRC8 family proteins are poorly understood, particularly in cancer. In the present study, we investigated LRRC8A in the most common cancers of the digestive system. LRRC8A proteins were found to be abundantly expressed in the esophagus, stomach, duodenum, colon, rectum, liver and pancreas. LRRC8A was elevated in 60% of colorectal cancer patient tissues, which was higher than that in patients with cancer of the esophagus, stomach, duodenum, liver and pancreas. Colon cancer patients with high‑ expressed LRRC8A had a survival time of 54.9±5.5 months, shorter than that of patients with low‑expressed LRRC8A (77.1±3.7). Moreover, survival time (52.6±7.3 months) of patients with metastases in the lymph nodes was shorter than that of patients without positive lymph nodes (72.2±3.6); patients with positive lymph nodes and an elevated LRRC8A expression had the highest mortality rate (~80%). These rates were not observed in rectal cancer. After LRRC8A protein was knocked down in colon cancer HCT116 cells, VRAC currents, migration and tumorigenesis in nude mice were significantly inhibited. In conclusion, we propose that LRRC8A could be a novel prognostic biomarker for colon cancer patient survival, and that the elevated expression of LRRC8A may enhance cancer cell growth and metastasis, and worsen the outcome of patients.

Estradiol activates chloride channels via estrogen receptor-α in the cell membranes of osteoblasts

Estrogen plays important roles in regulation of bone formation. Cl^- channels in the ClC family are expressed in osteoblasts and are associated with bone physiology and pathology, but the relationship between Cl^- channels and estrogen is not clear. In this study the action of estrogen on Cl^- channels was investigated in the MC3T3-E1 osteoblast cell line. Our results show that 17β-estradiol could activate a current that reversed at a potential close to the Cl^- equilibrium potential, with a sequence of anion selectivity of I^- > Br^- > Cl^- > gluconate, and was inhibited by the Cl^- channel blockers 5-nitro-2-(3-phenylpropylamino)-benzoate and 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid. Knockdown of ClC-3 Cl^- channel expression by a specific small interfering RNA to ClC-3 attenuated activation of the 17β-estradiol-induced Cl^- current. Extracellular application of membrane-impermeable 17β-estradiol-albumin conjugates activated a similar current. The estrogen-activated Cl^- current could be inhibited by the estrogen receptor (ER) antagonist fulvestrant (ICI 182780). The selective ERα agonist, but not ERβ agonist, activated a Cl^- current similar to that induced by 17β-estradiol. Silencing ERα expression prevented activation of estrogen-induced currents. Immunofluorescence and coimmunoprecipitation experiments demonstrated that ClC-3 Cl^- channels and ERα were colocalized and closely related in cells. Estrogen promoted translocation of ClC-3 and ERα to the cell membrane from the nucleus. In conclusion, our findings show that Cl^- channels can be activated by estrogen via ERα on the cell membrane and suggest that the ClC-3 Cl^- channel may be one of the targets of estrogen in the regulation of osteoblast activity.